The Science of Sealing Attic Wall Headers

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the science of sealing attic wall headers

M writing is detectable near-top. At this blog, pick Label: Sealing Wall Headers , here or at the right.

I think the process of heat transfer at attic walls, via paths at wall headers in an attic, can be imagined with this captioned photo:

Always in my work, wall headers are 100% sealed with flexible grout, as they are revealed. Gaps as here, are sometimes very large. Blackness of insulation pushed to the right speaks of the heat transfer process, now blocked by the sealing. Energy in convection pulls air down in some wall areas, and up in others, attempting to equalize attic and wall interior temperature. Dirt of outside air is deposited where passage is down, in the constant churn of air. The process has little to do with air infiltration, but rather is throttled action of attic floor pits.

The process in any home shifts with room use and weather outside. No one has attempted rigorous analysis or testing, or should. Yet, we need to estimate the benefits of sealing in defense of the fair cost of sealing, $200 to $500 in any home.

I estimate the savings as that of an inefficient attic floor pit, 10% bare area equivalent , of conditioned space ceiling area. The home of the photo above has 1366 sf heated space, and I charged a meager $200 for the 100% sealing with my flexible grout.

Estimated savings are $2.4*0.1*1366/3 = $109 per year. Two year simple payback. Bases of the math are: heating with a gas furnace 88% efficient, 4400 65° HDD, natural gas at real cost $2 per therm. I wish for math to show that annual savings are at least 20% of the $200 cost. That is achieved, however you do the math, and whatever you think is fair cost of energy. 

Recovery of invoiced cost could never be achieved if the home owner had hired the top HPwES contractor in Portland, Oregon:

This bid  is mean. It is knowingly based on lies. It is criminal.  Allowed and encouraged criminal conduct kills public trust and kills weatherization activity.


Failure to do 100% sealing of attic floors must be seen as inexcusable. Excuses are offered by powers in Portland, Oregon, that consequences are not measurable by a blower door , and methods tried are rejected by nearly all contractors  Final Evaluation Report - New Homes Air Sealing Pilot  . In a state of confusion, lacking conviction through scientific understanding, air sealing does not happen. None is required.


There is no longer an Energy Trust incentive for sealing air leaks in single-family homes in Oregon.  


And yet, in Oregon, the phony blower door purveyors of Home Performance with Energy Star , have large rewards from public funds, that are denied to a true believer in home sealing. This in effect is a conscious and very great harm against me, where my superior work is acknowledged, as I foreswear blower door madness. It is an action of Gresham's Law , even though the rewarded competition charge ruinously in their fraud. Usually, with counterfeit, good is ruined because it is less profitable to the public.

A Silly Test Of Wall Header Sealing, In Oregon

Here is the report of a silly test of air sealing in Oregon new-home construction:

(Gone!  The subject of this post was pulled down in 2016, replaced by a Pilot II study.)

Perhaps I am responsible for this. I discover the amendment only in August 2023 upon seeing that a reader in Tualatin Oregon would have been frustrated by the missing link.)

The newer report now at the link below, produced by an outside consultancy, Evergreen Economics and SBW Consulting, Inc.. Methods tested remain impractical and inapplicable to an existing home, thus dumb and irrelevant in my judgement. Please scroll to the bottom of this post to find review of this Pilot II report.  Still want use of sealing grout, and intelligent gaskets offered by Resource Conservation Technology. Want sealing in many existing homes to involve room-by-room wall drywall demolition and replacement, along with wiring and plumbing modernization.

Final Evaluation Report - New Homes Air Sealing Pilot II 

Photo Caption:
Figure 1. Photograph of sill sealer (pink band at top of wall) installed on the top plate prior to drywall installation (courtesy of Fluid Market Strategies; Manclark, 2013).

I judge that pink material in this photo is OWENS CORNING  FoamSealR Sill Gasket - 3 1/2 inch x 50 feet. x 1/4 inch,  roll polyethylene foam, sold in Home Depot stores  and elsewhere. Thickness might be as little as 3/16" in a less-available roll 4" wide and 86' long. Either is too thick, too wide and too incompressible, not imagined for this application.

I found edges of this material in November 2013, in a new Hillsboro, Oregon DR Horton home, both sides of each interior-wall header, upon installing a needed attic ladder. I couldn't reach out to exterior walls, those shown in the photo. I infer that all walls were treated, at top header only. The report of the air sealing test admits unhappiness of involved drywall installers. Drywall panels are placed with sliding action that tends to grab and roll the strips, and a deservedly-angry installer will rip out the damnation. The non-flat panel edges show, and that can't be hidden with ordinary mudding. There are better ways, of course.

The better ways to seal wall headers in wall construction include use of building gaskets by Conservation Technology, Baltimore, MD .

Here is copied descriptive text by Conservation Technology:


DRYWALL GASKETS: BG32 drywall gaskets are stapled to wall studs, top plates, and bottom plates before drywall is installed in order to prevent air flow between the drywall and the wood. They can be easily installed in any weather, even when wood is cold, wet, or dirty. The head of the seal compresses easily to less than 1/8”, so there is minimal pressure on the drywall. Always screw the drywall where gaskets are used.

Please know that Conservation Technology also offers best rim joist and sill plate gaskets:

At the associated Picasa web album , please find photo excerpts of the Conservation Technology products, and of exterior-wall header sealing achieved without gaskets where Swedish Tenoarm air/ vapor barrier material is employed. Buy the Tenoarm too from Conservation Technology.


Please see discussion of wall header sealing as weatherization retrofit, in the attic floor, at posts including this:
Sealing Wall Headers 
There find report that where my flexible grout is not commercially available, I offer free samples, and find that Custom tile grout is chemically very similar, and is available anywhere. Learn that spray foam is always inferior.


Silliness of the test accused? That a blower door measures effectiveness , and that a better sealing means was not found. Anything that requires a bribe for delivery, is wrong. No one should mind working with BG32 gaskets. They cost no more than the roll foam. Close to board ends, they do not affect drywall fit-up, shape and mudding. Wall header sealing must be made mandatory. The gaskets are an easier way, and can be delivered at outside walls not accessible from the attic. We don't need to retool, and do more stupid play with blower doors. Sealing will stop action of attic floor pits, far more than it affects exchange of outside air. Testing might instead consider the thermodynamics of interior wall flooding through wall header gaps of variable size. "Experiments" should never be conducted where conditions are not controlled, and where instruments are insensitive to results.

This goes beyond silliness, to deceit. There is a budget and strong intent , to continue the madness of the Energy Trust/ DR Horton Homes program despite now knowing better, where all involved are aware of my criticism.

It isn't only that wasteful experiments take place employing inappropriate gaskets. High-end new homes are being built in Oregon, where foolish gasketing is done as taught good practice. I found this gasket scrap under insulation on the floor of a new home attic. It was ripped from stapling as a probably-angry act. If by drywallers as is likely, no other sealing was offered in its place. This is not a less-expensive way to seal wall headers. Please, let us commit to sealing in all new homes and tear-down remodels, using good gaskets from Conservation  Technology.

Working in customer existing-home attics, I have not had opportunity of wall header sealing other than as forcing of flexible grout from the attic, upon interior walls. My practice in this is detailed in the advocacy web site, Plaster Repair How To, search Label: Wall Header Sealing . Gaps found have sometimes been huge, up to 1/4" and not possible of sealing with any practical gasket. I found such gaps even in my own home, well built by my uncle and oldest brother. Here are drippings from wet grout that penetrated stuffed-in fiberglass insulation, revealed in demolition for a kitchen remodel. I will always believe that surest sealing of headers is from the attic, before a careful manual placement of batt insulation.

Wall cavity air leakage is blocked by applying flexible gout and Structolite plaster at revealed wall headers. If I am able to seal along ceiling drywall and along sheathing or drywall of the adjacent rooms, that fully seals the wall cavities.

If the interior of wall header tops is not sealed by flexible grout or plaster, use building gaskets to seal the  interior face of wall headers.

Buy a coil of BG32 gasket from Conservation Technology. 

A 100 ft coil serving 100 lineal feet of wall at both top and bottom, is inexpensive. This coil cost me $40, plus $23.25 shipping. A local wholesaler could have sold the coil for $50. This is fully affordable and must be mandatory where cost is repaid with savings in about one year.

The gasket material is tough EPDM. Know that EPDM has 5 to 10 year shelf life and will remain serviceable indefinitely while not disturbed.

Split lengths for two gaskets, with scissors.

Attach with staples. Here on an interior wall, I will back up gap filling in the attic. See that I have sealed the existing drywall of the opposing room, with flexible grout. I have stuffed annuli around electrical wires, with Rockwool scraps.

On an exterior wall stuffed with insulation and with windows and doors, value of the BG32 gasket is uncertain. I didn't apply it before placing drywall to the right of this door. At 25 cents per ft, top-only, the cost is trivial. I got more placement practice, learning that 3/8" staples are needed.

The Evergreen Economics and SBW Consulting, Inc. Pilot II Report, April 21, 2016

Once again, it was thought wrongly that sealing effects could be observed with meaningful precision in blower door testing, to discriminate between homes  sealed and not sealed. Delta values were in the desired direction, but by only one standard deviation. These were not at all a test of insulation wind washing.

Tested Knauf Eco Seal was a by-gun goop-gasket application failure especially if applied with ambient below 60°F.

Available only in full truckload quantities.

Owens Corning Energy Complete is a messy and unreliable two-component foam application.

For each product,  half of homes in a study were sealed and half were not; mean for those not sealed.

Recommendation at report page 15, as wished:

Given the results, we do not recommend that the New Homes program move forward with the whole home and attic sealing measures tested in this pilot.

Energy Trust expensively justifies doing nothing with home air sealing. No incentives are offered.

 I am biased against the program intentions.

Sealing Wall Headers

Homes finished with drywall, or finish plaster over plasterboard, will have gaps seen in the attic floor. Wall drywall can't conform to both headers and (imperfect) studs, and fit give is predominantly at headers. At ordinary wall headers, there is a gap of at least 1/16", on one or both sides of the header. Gaps are reliably larger at wet walls where there are fit mismatches of doubled 2x4, and 2x8 studs. New homes still are rarely built with new airtight drywall methods, and probably will not employ best available gaskets.  Steel framing will result in many weatherization tragedies. 

The only useful instruction offered to me, for competence in weatherization, is that I must seal these gaps. That's it. Ten years ago, a class called Basic Air Sealing. For free, as it should be. I reject the HPwES training of weatherization workers of the past eight years, now delegated to very expensive and incompetent for-profit trainers. HPwES trainers and practitioners tell the absurd lie that a blower door is the means and measure of weatherization. Sealing opportunities in an attic are never found while a house is disabled of usability under blower door test conditions. All opportunities are discovered by sight, as one makes progress through the job, sometimes over the course of several days.

I believe complete sealing of all wall headers is important, and do it without fail. It is made easier for me by installation of safe access, secure decking and lighting. I dig down even through deep loose-fill, in the rare instance where a wise home owner now wants access, as to deal with defective attic ventilation. 


Caulking is the usual sealing method, and I have tried everything offered. Gun-applied foam is fast. I have consumed several Sharpshooter X guns at replacement cost up to $50, and lots of regretted volatile cleaner, yes, claimed exempt VOC, making messes and still not preserving the life of a gun that might be idle for a month. I think a frozen gun is not worth the time of repair, with accelerating degradation. Tube-dispensed caulk goes fast with poor volume control, will not bridge gaps larger than 1/8", and is a tracking hazard on shoes.  




I always have flexible grout in hand in a one-pound tub, for interior work as in a can light annulus. This fingertip application is tedious, but I have not lost a couple hours readying a foam gun. The wetter the surface at application, even down into vertical surfaces, the better. The grout must be handled as paste, but dilutes and is carried into water, like platelets. Little material is needed to bridge a gap. Go back sometimes with repeat quick application. I won't likely step on a treated wall header, in the fifteen minutes before material is dry. Anything tracked could be removed by vacuum or damp sponge.  It is water-soluble until set.


The flexible grout is a plaster crack repair material, and much more. I advocate for it to be available everywhere, at my plaster repair blog, offering free samples with promise of impending use and posted report of the experience. I extend the same offer to weatherization advocates and contractors. In weatherization, we must experiment with the packaging. Perhaps the wetting might be by brush of material at paint consistency. Hand-packing paste into an Albion bulk gun was a time loser, with the same overfill problems that are wasteful of squeezed tube caulk. Availability for weatherization might come faster if the material is also used to seal joints of HVAC ducts. Goop presently used on ducts needlessly is not water based, is horribly sticky, and is awful on equipment and clothing. An elbow might not be permanently ruined for reuse, if sealed with grout, not goop, at its alignment seams. Longitudinal pipe seams, aiming up, would be easy to grout.


I am aided sometimes by ability to bag and reset loose fill insulation, using 55-gallon drum liners, always several for trash or for transfer, on a job. With only a few inches of loose fill, just brush away. 

Where I have failed to deliver my flexible grout as a commercial product readily-available, I will  provide free samples upon request, and advise use of Custom tile grout as the available alternative.

I had a large remnant of this from my kitchen remodel, That is a common experience. Find a use for it.  The Custom Fusion Pro may be preferable to less-expensive choices. Find it in any big box store. I believe its formula is very similar to my flexible grout, with superior pot life. With floor-toughness, lose sandability. Not sandable, it is yet useful too in wall patching.

Just don't get sucked into the foolishness of using spray foam.